This invention relates to organ-stimulating apparatus and has particular relationship to such apparatus having a catheter, which is secured in the apparatus by a set-screw unit and serves to transmit stimulation to the organ. An important demand imposed on this setscrew is that it seals the apparatus tightly against penetration of body fluids to the catheter. The setscrew is a relatively small object and is secured to the catheter during a surgical operation. It has been found desirable, for the purpose of precluding the loss of the setscrew on the operating table or elsewhere in the operating room, to maintain the setscrew in the organ-stimulating apparatus ready for use. To achieve this object it has been proposed that the setscrew be held in the channel where it is to be screwed in to secure the catheter by a self-sealing plug or silastic rubber. The plug also is intended to serve to prevent penetration of body fluids. This expedient has the disadvantage that it demands that the instrument for screwing in the setscrew be manipulated without seeing the head of the setscrew. It can readily happen that the setscrew is not properly screwed in and damages the thread which it is to engage without securing the catheter. In addition, the self-sealing plug is not entirely reliable in preventing the penetration of body fluids.
U.S. Pat. No. 4,141,752 granted Feb. 27, 1979 to Frederick J. Shipko for ORGAN STIMULATING APPARATUS AND INSULATING SET SCREW FOR SUCH APPARATUS (herein called Shipko) is typical of other prior art. In Shipko the catheter is secured by a setscrew around whose head an O-ring extends. The O-ring has a greater diameter than the well into which the head extends. The O-ring serves to retain the setscrew in the organ-stimulating apparatus before it is screwed in to engage the catheter and also to seal the apparatus against the penetration of body fluids. While this apparatus has operated reasonably satisfactorily, surgeons who have used it have demanded that the setscrew be held captive more positively. Shipko's setscrew also has a metallic strengthening cap embedded in a plastic head. Some surgeons have objected to this feature.
It is an object of this invention to overcome the drawbacks and disadvantages of the prior art and to provide organ-stimulating apparatus in which the setscrew, which secures the catheter, shall both effectively seal the apparatus against leakage of body fluids and be positively held captive while lending itself to ready manipulation.
It is another object of this invention to provide such a setscrew which, while uniquely suitable as a component of organ-stimulating apparatus, has general applicability.